Bone cement mixing and delivery systems are well known for mixing separate components of bone cement together to form a uniform bone cement mixture and then delivering that mixture to a target site. Typically, such systems employ a mixer having a handle for manually mixing the components. Once mixed, the mixture is then transferred to a delivery device such as a syringe or cannula. A cement cannula is a type of syringe with a large length to diameter ratio. This ratio provides a user with a large mechanical advantage and good tactile feedback. Physicians fill cannulae with bone cement. These cannulae are filled prior to delivering said cement to the target site of a body.
The syringe or cannula is used to inject the bone cement mixture into the target site. The target site may be an anatomical site such as a vertebral body or the target site may be in or near an implant. Examples of target sites include medullary canals for total hip arthroplasty procedures, vertebral bodies for vertebroplasty or kyphoplasty procedures, and other sites in which bone cement is required.
Often, bone cements used in these procedures have working times of 20 minutes or less before the cement begins to harden. Once the cement starts to harden, it is difficult, if not impossible, for the practitioner to continue to use the cement. Current systems require a great deal of user interaction in set-up, including mixing the bone cement components and manually transferring the cement to the delivery device. This allows for only a small amount of working time. Current delivery devices are available, as previously mentioned, in the form of a syringe or cannula, and each delivery device must be filled with bone cement before use.
There are a number of different medical procedures wherein prior to the start of the procedure, it is useful to have a number of cannulae prefilled with cement. One such procedure is a vertebral augmentation procedure, which includes kyphoplasty and vertebroplasty, where cannulae are preloaded with cement. Each cement filled cannula is, one at a time, placed in an access cannula. A plunger forces the cement into the target bone. In a vertebral augmentation procedure, it may be necessary to inject the cement from multiple cannulae into the patient. Accordingly often, prior to the start of most procedures, at least four cannulae are preloaded with cement.
A number of bone cement mixing and transfer systems allow cannulae to be filled only one at a time. In the event multiple cannulae prefilled with cement are required for a procedure, the person responsible for filling the cannulae must work quickly to pre-fill the cannulae in order not to delay the surgical procedure.
In the prior art, currently there exists a delivery system which provides for the filling of bone cement within multiple syringes. In this system, multiple syringes are sequentially spaced apart and are attached perpendicularly to a distal end of a delivery device. Each syringe is equipped with a valve. Once cement has filled the entire reservoir of a first syringe, the user turns the valve into the “OFF” position. Once in the “OFF” position, cement can no longer flow to the syringe. The cement is then able to fill a next syringe in the sequence. Once all syringes are filled, one at a time, syringes are then removed from the mixer.
While the above system offers some benefits over a single fill cement mixing and delivery system, it is not without its own disadvantages. The system does not simultaneously fill the syringes. The user is required to set the on/off states of the individual valves. Having to set these valves can add to the time it takes to fill the cannulae. Moreover, having to set these valves introduces the possibility of human error into the cannula filling process.